3,078,254 United States Patent Office Patiented Feb. 19, 1963 2 dine, 3,5-diethyl-4-vinylpyridine, etc.; similar mono- and 3,078,254 di-substituted alkenyl pyridines and like quinolines; HGH MOELECULAR POYMERS AND RAE HOS acrylic acid esters, such as methyl acrylate, ethyl acrylate; FOR THER PEREPARATION alkacrylic acid esters, such as methyl methacrylate, ethyl Robert P. Zelinski and Henry L. Hsieh, Bariesville, Ck.a., methacrylate, propyl methacrylate, ethyl ethacrylate, butyl assignors to Plai Eips Petroiesia (Coapay, a corpora 5 methacrylate; methyl vinyl ether, vinyl chloride, vinyli tion of Delaware dene chloride, vinylfuran, vinylcarbazole, vinylacetylene, No Drawing. Filed July 20, 1959, Ser. No. 328,053 etc. 20 Claims. (C. 260-45.5) The above compounds in addition to being polym This invention relates to polymers of increased molec 0. erizable alone are also copolymerizable with each other ular weight prepared by reacting terminally reactive poly and may be copolymerized to form terminally reactive mers with compounds containing active halogens. In one polymers. In addition, copolymers can be prepared using aspect the invention relates to solid polymers prepared by minor amount of copolymerizable monomers containing heat curing polymers obtained by reacting polymers con more than one vinylidene group such as 2,4-divinylpyri taining terminal alkali metal atoms with compounds con 5 dine, divinylbenzene, 2,3-divinylpyridine, 3,5-divinylpyri taining active halogens. In still another aspect of the in dine, 2,4-divinyl-6-methylpyridine, 2,3-divinyl-5-ethylpyri vention curing is carried cut in the presence of a conven dine, and the like. tional curing system. The terminally reactive polymers in addition to in As used herein, the term "terminally reactive poly cluding homopolymers of polymerizable vinylidene com mer' designates polymer which contains a reactive group 20 pounds and copolymers of conjugated dienes with vinyli at one or both ends of the polymer chain. dene compounds also include block copolymers, which It is an object of this invention to provide new and are formed by polymerizing a monomer onto the end of useful polymeric materials of increased molecular weight, a polymer, the monomer being introduced in such a and process for their preparation. maniher that Substantially all of the co-reacting molecules Another object of this invention is to provide self 25 enter the polymer chain at this point. In general, the curing polymers from polymers containing terminal alkali block copolymers can include combinations of homopoly metal atoms, and process for their preparation. mers and copolymers of the materials hereinbefore set Still another object of this invention is to provide cured forth. A detailed description of block copolymers con polymers from polymers obtained by reacting polymers taining terminal reactive groups and their method of prep containing terminal alkali metal atoms with compounds 30 aration is set forth in the copending application of R. P. containing two or more active halogens. Zelinski, Serial No. 796,277, filed March 2, 1959. This These and other objects of the invention will become application describes a process for preparing block co imore readily apparent from the following detailed de polymers from monomers included in the following scription and discussion. groups: (1) 1,3-butadiene, 2-methyl-1,3-butadiene, 1,3- The foregoing objects are realized broadly by react 35 pentadiene and vinyl-substituted aromatic hydrocarbons; ing a polymer containing terminal alkali metal atoms (2) vinylpyridines; and (3) vinyl halides, vinylidine ha with an organic compound containing at least two active lides, acrylonitrile, esters of acrylic acid and esters of halogens to obtain a polymer of increased molecular homologues of acrylic acid. The process comprises the weight. steps of initially contacting a monomer selected from In one aspect of the invention the polymer product is 40 those included in groups (1) and (2) with an organo subjected to heat whereby molecules of said polymer lithium compound in the presence of a diluent selected react with each other to form a cured polymer. from the group consisting of aromatic, parafiinic and In another aspect of the invention curing of the poly cycloparaffinic hydrocarbons so as to form a polymer mer product is carried out in the presence of a conven block; and, after polymerization of substantially all of tional curing system. 45 the selected monomer, contacting the aforementioned The monomers which can be employed in the prepara catalyst in the presence of the polymer block initially tion of polymers containing terminal alkali metal atoms formed and the hydrocarbon diluent with a monomerse include a wide variety of materials. The preferred mono lected from those included in groups (1), (2) and (3) mers are the conjugated dienes containing from 4 to 12 when the initial monomer is selected from group (1) and carbon atoms and preferably 4 to 8 carbon atoms, such 50 with a monomer selected from those included in group as 1,3-butadiene, isoprene, piperylene, methylpentadiene, (3) when the initial monomer is selected from group (2), phenylbutadiene, 3,4-dimethyl-1,3-hexadiene, 4,5-diethyi the monomer selected being different from the monomer 1,3-octadiene, etc. In addition, conjugated dienes con employed in the initial contacting. taining reactive substituents along the chain can also be The terminally reactive polymers are prepared by con employed, such as for example, halogenated dienes, such 55 tacting the monomer or monomers which it is desired to as chloroprene, fluoroprene, etc. Of the coniugated di polymerize with an organo alkali metal compound. The enes the preferred material is butadiene, with isoprene organo alkali metal compounds preferably contain from and piperylene also being especially suitable. In addi 1 to 4 alkali metal atoms, and those containing 2 alkali tion to the conjugated dienes other monomers which can metal atoms are more often employed. As will be ex be employed are aryl-substituted olefins, such as styrene, 60 plained hereinafter, lithium is the preferred alkali metal. various alkyl styrenes, paramethoxystyrene, vinylnaphthal The organo alkali metal compounds can be prepared ene, vinyltoluene, and the like; heterocyclic nitrogen-con in several ways, for example, by replacing halogens in taining monomers, such as pyridine and allinoline deriva an organic halide with alkali metals, by direct addition tives containing at least 1 vinyl or alphamethyl-vinyl of alkali metals to a double bond, or by reacting an group, such as 2-vinylpyridine, 3-vinylpyridine, 4-vinyl 65 organic halide with a suitable alkali metal compound. pyridine, 3-ethyl-5-vinylpyridine, 2-methyl-5-vinylpyri The organo alkali metal compound initiates the po. 3,078,254 3. 4. lymerization reaction, the organo radical being in ample, of the condensed ring aromatic compounds the corporated in the polymer chain and the alkali metal lithium-anthracene adduct is preferred, but the adducts of being attached terminally on at least one end of the lithium with naphthalene and biphenyl can be employed polymer chain. When employing polyalkali metal con with good results. Of the compounds of alkali metals pounds an alkali metal is attached terminally at each with polyaryl-substituted ethylenes, the preferred ma end of the polymer chain. The polymers in general will terial is 1,2-dilithio-1,2-diphenylethane (lithium-stilbene be linear polymers having two ends; however, polymers adduct). Ordinarily the organo dialkali metal com containing more than two ends can be prepared within pounds are more effective than others in promoting the the scope of the invention. The general reaction can be formation of the terminally reactive polymers. The illustrated graphically as follows: O organo dialkali metal compounds which have been set forth as being preferred, are those which when prepared Y-R-Y -- XCH - Y-R(CH-Y contain a minimum of the monoalkali metal compound. Organoalkali Butadiene The amount of initiator which can be used will vary metal compound depending on the polymer prepared, and particularly the 5 molecular weight desired. Usually the terminally reac O tive polymers are liquids, having molecular weights in Y- CAHs) -R- I CH6 x-n-Y the range of 1000 to about 20,000. However, depending on the monomers employed in the preparation of the or combinations thereof. polymers and the amount of initiator used, semi-solid and A specific example is: 20 solid terminally reactive polymers can be prepared having molecular weights up to 150,000 and higher. Usually the initiator is used in amounts between about 0.25 and about 100 millimoles per 100 grams of monomer. Formation of the terminally reactive polymers is gen In the specific example 1,4-addition of butadiene is erally carried out in the range of between -100 and shown; however, it should be understood that 1,2-addi --150° C., preferably between -75 and --75° C. The tion can also occur. particular temperatures employed will depend on both While organo compounds of the various alkali metals the monomers and the initiators used in preparing the can be employed in carrying out the polymerization, by polymers. For example, it has been found that the far the best results are obtained with organolithium 30 organolithium initiators provide more favorable results compounds which give very high conversions to the at elevated temperatures whereas lower temperatures are terminally reactive polymer. With organo compounds required to effectively initiate polymerization to the de of the other alkali metals, the amount of monoterminally sired products with the other alkali metal compounds. reactive polymer, that is, polymer having alkali metal at The amount of catalyst employed can vary but is pref only one end of the chain is substantially higher. The erably in the range of between about 1 and about 30 alkali metals, of course, include sodium, potassium, lith millinoles per 100 grams of monomers. It is prefered ium, rubidium, and cesium.